In the medical field, it is often required that a medical practitioner manipulate an intracorporeal device within a body cavity of a patient. The device may be used for therapeutic or diagnostic purposes. Sometimes, the device includes an elongated drive shaft extending through a catheter and leading to an operating head at the distal end of the device. The drive shaft may rotate and thereby rotate the operating head. In addition to the drive shaft, the catheter may also include a guide wire, conduit, protective sheath, etc.
A general challenge in using an operating head is that it is often difficult for the operating head to reach the area of interest. The intracorporeal device must usually be routed along a tortuous path, through various internal structures within the body before arriving at the target site. For example, an obstructed blood vessel may be located in peripheral vessels, coronary vessels, cranial vessels, or other areas. In order to be directed through sharp bends in the path to the target site, such as sharp bends in blood vessels, it is desirable for the device to be as flexible as possible and allow the operating head to be directed at various angles relative to the longitudinal axis of the drive shaft and catheter. Moreover, the requisite small size of components required to be translated through vessels may limit performance of the device.
Furthermore, once the operating head is located at the site of interest, it is sometimes difficult to place the operating head into the appropriate operating position relative to the target site, e.g. an obstruction. The target site may be located in various places in a body cavity, such as along the walls of a lumen, e.g. a blood vessel. In addition, the operating head often needs to be operated within small confines of the interior body cavity. Accordingly, it would facilitate placement and operation of the operating head if the device was flexible such that the operating head could be oriented at various angles within the body cavity.
In intracorporeal devices in which an operating head attaches to a drive shaft, the drive shaft and catheter provide at least some flexibility along the lengths of the drive shaft and catheter in order to move the device within the body. However, flexibility of the device is usually compromised in the area where the drive shaft is fixed to the operating head at the distal end of the device. In most systems, the drive shaft is fixed to the operating head to translate rotational torque from the drive shaft to the operating head. Furthermore, the catheter must have a mechanism to support the rotating operating head. As a result of the hardware require to couple the operating head to the drive shaft and fixed catheter, the operating head may have limited ability to reach and access the target site.
Moreover, any flexibility provided for the operating head, e.g. tilting, must also occur within a controllable range of angles. Where an operating head is allowed to freely move or pivot, the operating head may be excessively collide with beneficial material, such as a vessel wall or a stent, causing damage to beneficial material.
Existing intracorporeal devices generally do not provide effective flexibility of the operating head at the junction between the drive shaft and operating head. Some prior systems use one or more gears and pins to pivot the operating head. Various of these devices are described in U.S. Pat. Nos. 5,792,165 and 5,383,888. Examples of such devices have a cutting portion with two pieces that come together to snip or pinch the unwanted matter. The cutting portion pivots about a pin by engaging gear teeth. However, operation of this gear-type of bearing system would result in high friction if the operating head were rotated at high speeds. Furthermore, some applications, e.g. cutting systems used in the vasculature system, require a very small cutting head, but it is difficult to design such a miniscule intracorporeal device using the gear-type bearing system.
A further challenge of designing high performance and reliable intracorporeal devices is that the devices are often subject to a variety of forces that can create strain on device components. For example, a force is created when the operating head contacts target matter and the device is subjected to a thrust load along direction of the length of the device. In addition, where the operating head rotates, the device is subject to rotational forces. At the same time, the distal components of intracorporeal devices need to be small in order to be manipulated within a small body pathways and cavities, e.g. lumens. The small components are more vulnerable to damage from heavy loads. It is essential for the device to be able to absorb the loads during an operation without having its components wear down and fail while in use.
An additional challenge of distal components of the operating head is that channels are sometimes required to aspirate or infuse liquid, blood or materials from or to the site of operation. Thus, flexibility of the operating head must not restrict flow through the device.
It is therefore desirable to provide a system for mounting an operating head to a drive shaft and catheter that provides flexibility at the operating head for easy manipulation within a body. The system should allow for controlled tilting of the operating head with respect to the catheter and/or drive shaft. It is further desirable for the mounting system to have small dimensions and support radial and/or thrust loads experienced during rotation and operation of the device. It would be further advantageous for the system to provide for aspiration or infusion of fluids or materials. The present invention fulfills these needs and provides further related advantages.